Long Weird Lesion type of growth under my tongue

Long Weird Lesion type of growth under my tongue - Sudden I have a big lesion on the underside of my mouth, under the tongue, it sort of scares me as it looks like a mini second tongue. It happened very quick - under 5hrs - I think, it was throbbing down there so I kept touching it with my tongue, by the time I got home it was big and red! Today, it has some whiteness to the end and looks like thick pus coming out but its getting slightly smaller. My doctor says he hasn t really seen this sort of thing but guesses its a lesion. I m not so sure, it looks really odd as it is not a circular bump but a long sort of flap of skin.